Superheterodyne receiver for ultrashort waves



me 16, 1936. M VON ARDENNE Q 2,044,374

SUPERHETERODYNE RECEIVER FOR ULTRASHORT WAVES Filed June 14, 1932 Patented June 16, 1936 S'UPERHETERODYNE RECEIVER FOR ULTRASHORT WAVES Application June 14, 1932, Serial No. 617,115 In Germany June 18, 1931 3 Claims.

As well known, the wireless transmission of intelligence (wireless telephony, image transmission, wireless television and the like) by means of ultra-short waves is in numerous cases of considerable advantage. This is based principally on the fact that it is possible to include in the ultra-short wave locality a large number of transmitters, all of which may be allowed to possess a relatively large width of band, something which is not to be avoided more particularly in connection with the transmission'of television images.

An appreciable disadvantage accompanying the transmission of intelligence with the assistance of ultra-short waves has heretofore made it impossible to utilize the advantages of ultrashort waves, which advantages are of a considerable kind in themselves, viz., it is not possible to effectively amplify ultra-short waves in simple fashion. The ultra-short wave high-frequency amplifiers hitherto known possess the disadvantages that the same on the one hand result in merely a very slight amplification, which moreover is only possible by the use of a plurality of resonance circuits, and that the same accordingly possess a very small width of band. Amplifiers of this character are naturally not capable of being employed if it is exactly the above-stated advantages of the ultra-short waves, viz., the possibility of being able to place a plurality of modulated carrier waves with wide frequency bands side by side, which are to be made use of.

The subject matter of this invention is constituted by a method which enables a relatively wide frequency band of, for example, periods to a million of periods to be transmitted with considerable amplitude by means of ultra-short waves. The method according to the invention is in the nature of a transposition process, which has only been rendered possible by the latest development in connection with aperiodic highfrequency amplifiers for the wave range between approximately and 100 metres. In accordance with the invention, the ultra-short wave second rectifier, and passed to: an aperiodic low frequency amplifier, which acts in suitable fashion on the frequency band to be transmitted.

The invention is described in the drawing in a possible form of embodiment. In the drawing l is an ultra-short wave aerial, for example with parabolic reflector, and 2 the oscillatory circuit, which consists of the inductance 3 and the condenser A, and is tuned to the ultra-short wave.

5 is the oscillation generator, which operates according to the three-point connection system, and consists of a thermionic valve 6, the tapped s-coil 1, the condenser 8, a grid blocking condensena leakage resistance and the requisite batteries 9, Ill and II. The oscillation produced by this generator is induced over a coil l2 into the grid circuit of the valve 13, which acts as the rectifier. This valve is preferably furnished with a screening grid, in order to permit of a sufficiently good rectifying and amplifying effect in respect of the high frequency. By reason of the unavoidable, relatively large loading capacity of the anode circuit, the valve [3 acts as rectifier for the extremely high frequencies.

The intermediate frequency amplifier consists of the valves l4 and I5, furnished with screening grids in the same manner as the demodulator valve and coupled with each other and with the tube [3 and the following demodulator tube aperiodically in order to permit of a sufficient frequency-independent amplification in the requisite frequency zone of approximately 3-15 million periods corresponding with 100-20 In. wave length. For this purpose in the anode circuits of the tubes I3, M, It: may be included chokes l6, l1, l8; the anodes of these tubes are connected with the control grids of the following tubes by coupling condensers I9, 20, 2| and the control grids of the tubes l4, l5 are connected with the cathodes of the tubes l4, I5 by leaking resistances 22, 23. However, ohmic resistances may also be employed as anode resistances insofar as the same are suitably dimensioned, more particularly with regard to the coupling condensers I9, 20 and 2| and the grid resistances 22 and 23. The intermediate frequency wave occurring at the anode of the final intermediate frequency valve l5 and modulated with the frequency band to be transmitted is passed to the intermediate frequency demodulator 24 through the medium of a condenser 2!. The frequency band occurring at the anode resistance 25 thereof is conducted now to an aperiodic amplifier 26, which is so dimensioned that the same ensures a sufficiently frequency-independent amplification of the frequency band to be transmitted, which is caused to take effect in the consuming apparatus 21, for example, therefore, in the television receiver. For this purpose the coupling condensers of the amplifier 26 are furnished with a capacity of approximately 5000 to 10000 cm., and anode resistances of '7 000 to 15000 ohms with relatively large grid resistances of approximately 5-10 megohms are employed. As amplifier valves for this low frequency wide band amplifier there are preferably employed screening grid valves.

As already stated above, it is possible with the use of the method as described to obtain by means of ultra-short waves the transmission of wide frequency bands strong in amplitude and a frequency-independent amplification. Naturally, the invention may be employed not only in connection with the transmission of one or more wide frequency bands, but also upon the transmission of a plurality of high frequencies, more particularly when it is desired to amplify the same by means of common aperiodic amplifiers. Further, the invention is not limited to use of the amplifiers, demodulators and oscillator as described, and these may naturally also be replaced by devices acting in similar or like fashion.

I claim:

1. A super-heterodyne radio receiver for receiving ultra-short carrier waves modulated by wide frequency bands up to several million periods preferably for television purposes consisting of an ultra-short wave antenna circuit, an ultra-short wave heterodyne generator, an aperiodic intermediate frequency amplifier having a plurality of valves, a detector valve coupled to the output of the intermediate frequency amplifier, and an aperiodic low frequency amplifier with an output circuit, means for coupling said antenna circuit and said heterodyne generator with the input circuit of the first valve of said intermediate-frequency amplifier, and means comprising a loading capacity in the anode circuit of said first valve in the intermediate frequency amplifier having such reactance that the signal and locally generated oscillations are demodulated in said valve.

2. A super-heterodyne radio receiver for receiving ultra-short carrier waves modulated by Wide frequency hands up to several million periods preferably for television purposes consisting of an ultra-short wave antenna circuit, an ultrashort wave heterodyne generator, an aperiodic intermediate frequency amplifier having a plurality of valves, a detector valve coupled to the output of the intermediate frequency amplifier, and an aperiodic low frequency amplifier with an output circuit, means for coupling said antenna circuit and said heterodyne generator with the input circuit of the first valve of said intermediatefrequency amplifier, and means comprising a loading capacity in the anode circuit of said first valve in the intermediate frequency amplifier having such reactance that the signal and locally generated oscillations are demodulated in said valve, said intermediate frequency selected high in comparison with the highest modulating frequency and sufliciently low for permitting the aperiodic amplification.

3. A super-heterodyne radio receiver for receiving ultra-short carrier waves modulated by wide frequency bands up to several million periods preferably for television purposes consisting of an ultra-short wave antenna circuit, an ultrashort wave heterodyne generator, an aperiodic intermediate frequency amplifier having a plurality of valves, a detector valve coupled to the output of the intermediate frequency amplifier, and an aperiodic low frequency amplifier with an output circuit, means for coupling said antenna circuit and said heterodyne generator with the input circuit of the first valve of said intermediate-frequency amplifier, and means comprising a loading capacity in the anode circuit of said first valve in the intermediate frequency amplifier having such reactance that the signal and locally generated oscillations are demodulated in said valve, said intermediate frequency selected high in comparison with the highest modulating frequency and sufficiently low for permitting the aperiodic amplification, in the anode circuits of the intermediate-frequency amplifier tubes and of said detector tube are arranged anode chokes, and the coupling elements of said low frequency amplifier consisting of anode resistances in the order of 7000-15000 ohms, of coupling condensers in the order of 5000-10000 cm. and of grid-leak resistances in the order of 510 megohms.

NIAN FRED VON ARDEN NE. 

